First a couple of system details:
Are you using the client / server version of BR?
If a client session was terminated abormally, then the BR session for that user is still running on the server.
Have to either goto the server and run task manager, and quit the BR session for that user to clear it.
If you have WSID=Unique in wbconfig, using a local pc version of BR. this could also be a corrupt wbserver.dat file.
Delete the wbserver.dat file after exiting BR.
Hope this helps.